The present invention relates to a digital broadcasting system for providing the program and data to the mobile station on a vehicle with digital broadcasting, and to an information service station and a mobile terminal for storing and distributing the program and its related data which the mobile object can not received.
At present, as for the information system used on the vehicle, map navigation systems come into wide use in the country of the inventors. An upgrading the software of the map navigation system, however, requires technical knowledge, and it is difficult for general users to upgrade the software. In the countries outside out country, the onboard navigation systems are designed with a general purpose OS, and various programs are executed on it. A map navigation system is under developing not as a dedicated terminal like a conventional map navigation system but as an onboard computer system designed with emphasis on expandability.
An Intelligent Transportation System (ITS) is under discussion as a next generation onboard information system. An information service to the moving vehicle is provided actively in ITS. Under the present circumstance, only transient traffic information such as traffic jam status and expected travel time is practically in service.
In order to meet the user's needs mentioned above and transfer information efficiently to plural targets, such a way that the user can service the data and software of the navigation system in the onboard terminal by broadcasting the data though digital broadcasting and/or FM broadcasting is introduced (Japanese Patent Application Laid-Open Number 8-87234 (1996), and Japanese Patent Application Laid-Open Number 8-195690 (1996)). By integrating the network represented by GPS and Internet and the data broadcasting, a navigation system enabling various services including upgrading of the map data at the onboard terminal with a computer is proposed (Japanese Patent Application Laid-Open Number 10-153440 (1998)).
As described above, there are some proposals found here and there which enables to register the new version of the software and control its versions in the onboard terminal by using the multiplexed data broadcasting. However, as the current information transmitted from the broadcasting station is transient (or intermittent), the user can not obtain his or her necessary data when the data broadcasting is not on air. The data distribution part of the satellite and beacon systems has a limited transmission capacity. For example, the communication satellite for digital television has 20 to 30 Mbps per 1 channel. When trying to transmit massive data and programs in such a circumstance, it is impossible to transfer all the data in a short period. In trying to repeat data broadcasting including past data, the transmission efficiency is reduced, which results in the failure of providing various data services.
Owing to this circumstance, even when the user needs a new program for the onboard terminal or tries to upgrades the version of the data in order to obtain the services provided for the onboard terminal, the transmission data is reluctantly transmitted from the data distribution parts including the satellite and beacon systems. This means that it is difficult for the user to obtain his or her necessary data when the user needs it. On the other hand, as the electric power is not applied to the onboard terminal while the vehicle stops, the data can not received. As a result, there is such a problem that, whether the required broadcasting data has been broadcasted can not be even recognized, and that the data can not be obtained.
What is proposed in Japanese Patent Application Laid-Open Number 8-87234 (1996) is a system that the data is stored in plural repeater stations with broadcasting and the onboard terminal of the individual vehicle picks up the data from its neighboring repeater station if required. However, if the name of the broadcasting data which could not be received at the onboard terminal is not recognized by the onboard terminal, the user can not even request what he or she asks to receive from the repeater station.
So far, there is no consideration in the conventional proposals for the onboard terminal to know what data was broadcasted in past and what data could not be received. Searching a mechanism for informing easily the name of the broadcasted data and so on without increasing the amount of data is a critical problem. If the name of the data (and preferably the location of the data) which should be transmitted again can be found also in the repeater station, the efficiency in the transmission processing and the storage processing can be increased and the service provided in response to the request for the broadcasting data name from the onboard terminal can be realized.